ICAS External Seminar

Presented by Delphine Farmer, Colorado State University

Seeing the forest for the trees: Sources and sinks of organic and black carbon

Host: Dom Spracklen

Abstract: Forests play an important, but poorly understood, role in the carbon balance of the atmosphere. Volatile organic carbon emitted from the biosphere can be oxidized rapidly – even within the forest canopy. This oxidation chemistry contributes to tropospheric ozone pollution and the production of secondary organic aerosol. The molecular identity and structure of organic carbon influences its potential fate and thus climate and air quality impact. This is particularly important over pine forests dominated by monoterpene emissions, including the Manitou Experimental Forest Observatory in Colorado, USA. At this site, we observe a persistent upward flux of organic acids that allows us to trace the role of ecosystem emissions and chemistry through the seasons. However, forests are not only sources of organic carbon – they are also sinks. Wet and dry deposition removes carbon-containing trace gases and particles, but is a poorly understood process. Black carbon is an inert tracer for studying the relative contribution of wet versus dry deposition in controlling the fate of particles. I will describe a series of field measurements and laboratory experiments that allow us to investigate organic carbon emissions, chemistry and deposition – and new approaches to measuring particle deposition over the terrestrial biosphere.

Bio: Delphine Farmer is an Associate Professor in the Department of Chemistry at Colorado State University. She received her BSc in Chemistry from McGill University, and her MS (Environmental Science, Policy and Management) and PhD (Chemistry) from the University of California Berkeley. She held a NOAA Climate and Global Change Postdoctoral Fellowship at the University of Colorado in Boulder before starting her independent career. Dr. Farmer’s research focuses on the sources and fate of reactive trace gases and particles in the atmosphere, with particular emphasis on understanding deposition processes. Her work includes both laboratory and field studies of both indoor and outdoor environments, as well as the development of new mass spectrometry techniques. Dr. Farmer is currently a Visiting Professor at Vrije Universiteit, Amsterdam.

The seminar will be followed by cake and coffee in the School foyer.